The MP3 digital audio format has been extended to allow the inclusion of digital rights management technology.

The Fraunhofer Institute - the company behind the development of MP3 - will demonstrate the technology during a presentation at CeBit later this month.

Fraunhofer's Light Weight Digital Rights Management System (LWDRM) was launched last year. The system uses digital signatures to overcome what the Institute has called the consumer unfriendliness of existing approaches to DRM.

LWDRM requires the user to register with a digital signature certification authority. The technology blocks all attempts to copy the file until the owner is "willing to autograph the purchased content with his personal digital signature". At that point, the file can be transferred to a portable player or to "family and friends, adhering to the prevalent legislation and the rules of fair use", Fraunhofer said.

If the user shares the file via Kazaa or some other P2P network, his or her digital signature reveals just who "leaked" the content, and appropriate action can be taken. Content is protected using Fraunhofer's own watermarking technology and AES-level encryption.

Fraunhofer is aware that plenty of folk won't want to register for a digital signature, but it reckons its system at least allows such people to listen to music - they are simply prevented from sharing it.

LWDRM was originally developed for MPEG 4 audio and video, and according to Fraunhofer, has been implemented in solutions since 2002. However, the update brings DRM to the MP3 format. It's not the first time anyone has attempted to add DRM to MP3: Liquid Audio experimented with it in the early days of Internet-delivered digital audio and prior to its collapse Napster was working on a similar technology of its own.

Plenty of other DRM systems exist, of course, with Apple, Microsoft and Real Networks all offering copy-protection mechanisms that have been implemented in all the major digital music download services, all of them tackling the same consumer unfriendliness mentioned by Fraunhofer.

And like other DRM systems, LWDRM requires a new, compatible player to be used - or at least have their firmware upgraded. However, it does provide companies keen to get into digital music distribution a way of doing so securely without accepting the limitations of Apple's service - primarily the fact it only works with the iPod - or aligning themselves with Microsoft.

That said, none of the other DRM systems require users to certify themselves with a third party, the cost of which - quite apart from its inherent consumer unfriendliness - may put would-be LWDRM users off. Of course, there's nothing to stop music vendors issuing their own digital signatures, tied to the buyer's credit card details and the system on which the track was downloaded - much the way Apple's FairPlay DRM technology works. ®